The present invention pertains to fiber optic cables and, more particularly, to obtaining access to stacks of optical fiber ribbons contained in buffer encasements.
Optical fiber is a very popular medium for large bandwidth applications, and as a result there is a demand for fiber optic cables with greater numbers of optical fibers. In response to demands for increased optical fiber count in fiber optic cables, optical fiber ribbons have been developed. Optical fiber ribbons are planar arrays of optical fibers that are bonded together as a unit. Optical fiber ribbons are advantageous because many ribbons can be stacked on top of each other to form a stack of optical fiber ribbons.
It is conventional for stacks of optical fiber ribbons to be incorporated into two different types of fiber optic cables that are generally referred to as xe2x80x9ccentral-corexe2x80x9d and xe2x80x9cloose-tubexe2x80x9d cables. In the central-core design, a stack of optical fiber ribbons are contained within a central tube, which is located at the center of the fiber optic cable. Further, strength members are positioned between the central tube and an outer plastic jacket of the cable. In contrast, loose-tube fiber optic cables typically include a number of relatively small buffer tubes that are positioned around a central strength member, and each buffer tube encloses a stack of optical fiber ribbons. The buffer tubes are longitudinally stranded around the central strength member, meaning that the buffer tubes are rotated around the central strength member along the length of the fiber optic cable.
It is conventional for the above-referenced tubes to be cut to obtain access to the optical fibers therein. Access may be desired for purposes of inspection, for the purpose of forming a splice between optical fibers, or the like. Such cutting of tubes that contain optical fibers is inherently risky because it is possible that one or more of the optical fibers contained in the tube will be undesirably damaged by the cutting. The possibility of such undesirable damage is ever increasing as fiber optic cables become more densely packed with optical fibers. Inadvertently damaging optical fibers in densely packed fiber optic cables can be very disadvantageous, because it can be expensive to repair or rebuild such cables.
The present invention solves the above problems, and other problems, by providing a buffer encasement having a longitudinally extending interior surface that extends around and defines a longitudinally extending passage containing optical fibers, with the interior surface closely bounding the stack, and the buffer encasement being easily removable from the stack. The optical fibers are preferably arranged as a stack of optical fiber ribbons.
In accordance with one aspect of the present invention, the buffer encasement is easily removable from the stack because the buffer encasement is thin and is constructed of a material that is capable of being easily torn. More specifically, each optical fiber ribbon comprises a pair of longitudinally extending opposite edges and a pair of longitudinally extending opposite surfaces that extend laterally between the edges, and each optical fiber ribbon has a thickness defined between its opposite surfaces. In an end elevation view of the buffer encasement, at least a majority of the buffer encasement has a thickness defined between interior and exterior surfaces of the buffer encasement. The thickness of the buffer encasement is not substantially greater than the thickness of each of the optical fiber ribbons.
In accordance with another aspect of the present invention, the buffer encasement defines a longitudinally extending weakened portion that is capable of being more easily torn than the remainder of the buffer encasement. The weakened portion is operative so that when the weakened portion is torn the buffer encasement defines longitudinally extending edges on the opposite sides of the tear. The edges can be separated from one another to define an opening therebetween through which the stack of optical fiber ribbons can be accessed.
In accordance with another aspect of the present invention, the buffer encasement has a pair of longitudinally extending edges that can be separated to define an opening therebetween through which the stack of optical fiber ribbons can be accessed. More specifically, the buffer encasement can be in the form of a longitudinally extending piece of tape having longitudinally extending opposite edges defining an overlapping configuration so that the tape encloses the stack of optical fiber ribbons. The edges of the tape can be separated to provide a nonoverlapping configuration in which an opening is defined between the edges and through which the stack of optical fiber ribbons can be accessed.
In accordance with another aspect of the present invention, the buffer encasement is easily removable from the stack because the buffer encasement is easily torn. In accordance with one example, the buffer encasement is constructed of a polymeric material that contains one or more fillers that increase the tearability of the polymeric material.